For film applications requiring good optical properties (low haze, high gloss, high see-through clarity) such as bread bags and zipper storage bags, converters typically use blends of LDPE and LLDPE or LDPE and mLLDPE. The cast film or blown film processes are the usual methods for making these films. These films generally show deficiencies in the following areas that would be desired for improvement.
Toughness—Low puncture properties limit the ability to create thin films. Poor toughness increases the potential for film failure and consequently spoilage of the bags' contents.
Film Stiffness—Even with improved toughness, if the current films are down-gauged, the resulting film becomes flimsy. Lower stiffness films are more difficult to process in down-stream operations (slitting, printing, bag-filling, etc.). In addition, consumers may associate a flimsier bag as a lower quality product.
Product Freshness—Many clarity film applications are used for the packaging of perishable food items. A bag that enables a product to have a longer shelf life is desired because that bag can limit the amount of product that becomes stale while sitting on the grocery store shelves.